Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds genuinely non-redundant behavioral context: the call is free, requires no payment, and falls under an open-data carve-out — exactly the kind of cost/auth fact annotations cannot express.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core identity ('FREE price list for every Tollbridge surface'), followed by the payload contents and the cost caveat. Three compact sentences with little waste, though 'FREE', 'Free per the ... carve-out' and 'No payment required' restate the same point three times.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return shape need not be described, and the description still enumerates the four data categories the agent will receive. The only real gap is the undocumented optional 'payer' parameter, which leaves one invocation decision unexplained.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There is one parameter, 'payer', with 0% schema description coverage, and the description never mentions it or explains what supplying an address would change about the returned prices. With low coverage the description is expected to compensate, and it does not, leaving the parameter's meaning and optionality unstated.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource (a price list) and enumerates its contents: per-endpoint USDC prices, subscription plans with effective per-credit rates, booster credit packs, and the credit anchor. No sibling tool in the list covers pricing, so the agent can immediately separate this from the calls/arena/risk tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly positions the tool in the workflow: 'the exact numbers an agent needs before calling any paid tool.' That gives a clear trigger condition. It does not name an alternative or state exclusions, but there is no competing pricing sibling to route away from.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.